1. Field of the Invention
The present invention relates to a coreless rotary electric machine.
2. Description of the Prior Art
The above-mentioned type of rotary electric machine, that is, a rotary electric machine having such coreless rotary coil which has an end connection only at its one side and which is mounted on a shaft rotatably within the magnetic field of a stator field magnet is known, for example, by Japanese Patent Application Publication No. 22,361/1974 and DOS 2,126,199.
In the art of acoustic apparatus and device such as tape recorder and video tape recorder nowadays there is an increasing desire for miniaturization and higher performance. To satisfy the desire it is essential to reduce the size and weight of the rotary electric machine used in the acoustic apparatus while further improving the capacity and performance of the rotary machine. It is evident that the above-mentioned type of coreless rotary electric machine is most suitable for this purpose.
However, miniaturization and improvement of performance of the conventional coreless rotary electric machine can not be attained only by reducing the size and improving the performance of individual component parts of the machine. It is absolutely necessary to change the structure and arrangement of rotary coil and commutator in the coreless rotary electric machine employing a new conception of design. Considering the mounting place and space volume available for a rotary electric machine in an acoustic apparatus as mentioned above, it is preferable to use in such acoustic apparatus a flat type rotary electric machine. However, designing of a rotary electric machine having a flattened form involves many limitations, in particular for the conventional arrangement of coil, magnet, yoke, brush, commutator etc. If the well-established arrangement of conventional rotary electric machine is changed for the purpose of flattening, then the efficiency may be reduced remarkedly and also reasonability in structure may be lost to some extent. In fact, all the designs hitherto proposed for attaining the purpose have been realized at the sacrifice of efficiency and structural reasonability.